Hashtable

Variable name

val varname_of_string : ?hyphen:char -> string -> string

varname_of_string ~hyphen:c s Transform a string s into a variable name,
following this convention: no digit at the beginning, lowercase, only a-z
and 0-9 chars. Whenever there is a problem, use an hyphen.

val varname_concat : ?hyphen:char -> string -> string -> string

varname_concat ~hyphen p s Concat variable name, removing hyphen at end
of p and at beginning of s.